The Human Microbiome Project
There are trillions of microorganisms living in symbiosis with the human body, making up what scientists call the human microbiome. Bacteria in an average human body number 10 times more than human cells; they make up about one to three percent of your total body mass, or two to six pounds in a 200-pound male. Microbial communities exist in your nose, mouth, skin, gut, and urogenital tract. (They also live everywhere else you’d expect, including other animals and in plants.) They consist of eukaryotes, archaea, bacteria, and viruses, some of them creating essential nutrients, others helping our immune system. The human microbiome differs from person to person, between races and ethnicities; it’s informed by geographical context, diet, and states of health. It’s a dynamic, a living part of each human’s body, changing and evolving over an individual’s lifespan. In short: It’s the stuff that isn’t quite “you” that’s nevertheless essential to your body’s daily function.